1. Field of the Invention
The present disclosure relates to a molded case circuit breaker (abbreviated as a “MCCB” hereinafter), and more particularly, to a movable contact arm and a movable contact arm assembly for a circuit breaker capable of removing adhesive materials formed such that foreign substances such as scattering materials due to arc generation is stuck to a shaft.
2. Description of the Related Art
The MCCB is an electric power device having a function for switching a relatively low voltage electric power circuit with several hundred volts and a protection function capable of detecting a fault current such as an over current or short-circuit current when it occurs on the circuit to automatically trip the circuit, thereby protecting the circuit and an electric load device connected to the circuit.
Such a MCCB, as is well known, may largely include a stationary contact arm configured to be electrically connected to the power source side of the circuit, a movable contact arm configured to be electrically connected to the load side of the circuit and revolved to a closed position brought into contact with the corresponding stationary contact arm and an open position separated from the corresponding stationary contact arm, a switching mechanism configured to provide a driving force for driving the corresponding movable contact arm to the closed or open position, a shaft configured to be revolved by a driving force from the switching mechanism so as to support the movable contact arm and constitute a movable contact arm assembly along with the movable contact arm, a trip mechanism configured to detect a fault current when it occurs on the circuit and trigger the switching mechanism to drive the movable contact arm to the open position, an extinguishing mechanism configured to extinguish an arc occurring during the switching of the circuit, and an enclosure for accommodating the constituent elements.
The present disclosure relates to a movable contact arm and a movable contact arm assembly among the constituent elements of the molded case breaker, and an example of the related art may refer to Korean Patent No. 10-1141537 (Title of Invention: Movable contact arm assembly for current limiting molded case circuit breaker) granted to the applicant of the present invention, and thus the detailed description of the illustrated configuration and operation will be omitted.
However, according to the related art, there is no solutions to the occurrence of a phenomenon of reducing or limiting the revolution radius to the closed position of the movable contact arm in which foreign substances such as arc scattering materials due to an arc generated during the switching of the circuit is stuck to the stopper portion of the shaft which determines the revolution limit to the closed position of the movable contact arm.
For the problems of obstructing the revolution radius of the movable contact arm and reducing the circuit switching performance due to such adhesive materials, there has been contrived a method for providing an additional synthetic resin remolded barrier having excellent heat resistance performance on a path between a contact portion generating an arc and an opening portion of the shaft to prevent adhesive materials from being generated, but it has caused a problem in which the production cost of the molded case breaker is increased due to additional elements and the installation space is limited due to the other existing elements of the molded case breaker.